Parallel transmission of preamble sequences with data layers for improved data detection

ABSTRACT

Methods, systems, and devices for wireless communications are described. In some systems (e.g., non-orthogonal multiple access (NOMA) systems), a base station may serve a large number of user equipments (UEs) on the uplink. To improve detectability for these uplink transmissions (e.g., if reference signals are not available for the transmissions), the UEs may implement parallel transmissions of preambles with uplink data. A UE may split the uplink data into one or more data layers, and may select one or more preamble layers to transmit superposed with the data layers. These preambles may be sequences known to both the UE and the base station to aid in detectability. The UE may assign different signature sequences to each of these layers based on cross-correlation values (e.g., assigning sequences with higher cross-correlation values to the data layers for improved detectability), and may scramble the layers into a single shared signal for transmission.

CROSS REFERENCES

The present application is a 371 national phase filing of InternationalPatent Application No. PCT/CN2019/079460 by CAO, et al., entitled“PARALLEL TRANSMISSION OF PREAMBLE SEQUENCES WITH DATA LAYERS FORIMPROVED DATA DETECTION,” filed Mar. 25, 2019; and to InternationalApplication No. PCT/CN2018/081542 by CAO, et al., entitled “PARALLELTRANSMISSION OF PREAMBLE SEQUENCES WITH DATA LAYERS FOR IMPROVED DATADETECTION,” filed Apr. 2, 2018, each of which is assigned to theassignee hereof and each of which is hereby incorporated by reference inits entirety.

BACKGROUND

The following relates generally to wireless communications, and morespecifically to parallel transmission of preamble sequences with datalayers for improved data detection.

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include fourth generation (4G) systems such asLong Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, orLTE-A Pro systems, and fifth generation (5G) systems which may bereferred to as New Radio (NR) systems. These systems may employtechnologies such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal frequency division multiple access (OFDMA), or discreteFourier transform-spread-OFDM (DFT-S-OFDM). A wireless multiple-accesscommunications system may include a number of base stations or networkaccess nodes, each simultaneously supporting communication for multiplecommunication devices, which may be otherwise known as user equipment(UE).

Some wireless communication systems (e.g., non-orthogonal multipleaccess (NOMA) systems) may support a large number of UEs transmittingdata on the uplink connection using non-orthogonal signature sequences.The wireless communications systems, however, may support a much smallernumber of reference signals (e.g., demodulation reference signals(DMRSs)) for transmission with this uplink data. For example, thewireless communications systems may support between four and twelveDMRSs within a slot, but may support many (e.g., hundreds or eventhousands) of uplink data transmissions using short or long signaturesequence designs during this time frame. In these cases, the limitednumber of DMRSs may result in a bottleneck of uplink transmissioncapabilities in a NOMA system, which may lead to inefficiencies and lesseffective communication.

SUMMARY

The described techniques relate to improved methods, systems, devices,or apparatuses that support parallel transmission of preamble sequenceswith data layers for improved data detection. Generally, the describedtechniques provide for supporting data detectability at a base stationin a non-orthogonal multiple access (NOMA) system (e.g., a massive NOMAsystem). A base station in a NOMA system may serve a large number ofuser equipments (UEs) on the uplink during a same time period (e.g., aslot), but may support a much smaller number of uplink referencesignals.

To improve detectability for uplink transmissions (e.g., if referencesignals are not available for the transmissions, for redundancy whenreference signals are available), the UEs may implement paralleltransmissions of some information (e.g., preambles) with uplink data. AUE may split the uplink data into one or more data layers, and mayselect one or more information layers, such as preamble layers, totransmit superposed with the one or more data layers. These preamblesmay, in some cases, be sequences or values known to at least one of, ifnot both of, the UE or the base station. The UE may assign differentsignature sequences to each of these layers based on some information,which may include one or more cross-correlation values (e.g., assigningsequences with higher cross-correlation values to the data layers forimproved detectability), and may scramble the layers into a singleshared signal for transmission. A base station receiving the signal maydecode the data based on the other information (e.g., the preambles).For example, the base station may perform channel estimation using thepreamble information, or may use the preamble information as priorinformation inputs in a message-passing procedure.

A method of wireless communications is described. The method may includeidentifying one or more data layers and one or more preamble layers fortransmission, determining a set of signature sequences for scramblingthe one or more data layers and the one or more preamble layers,assigning each signature sequence of the set of signature sequences to adata layer of the one or more data layers or a preamble layer of the oneor more preamble layers based at least in part on a cross-correlationmetric of the each signature sequence, scrambling the one or more datalayers and the one or more preamble layers into a shared signal usingthe assigned each signature sequence, and transmitting the sharedsignal.

An apparatus for wireless communications is described. The apparatus mayinclude means for identifying one or more data layers and one or morepreamble layers for transmission, means for determining a set ofsignature sequences for scrambling the one or more data layers and theone or more preamble layers, means for assigning each signature sequenceof the set of signature sequences to a data layer of the one or moredata layers or a preamble layer of the one or more preamble layers basedat least in part on a cross-correlation metric of the each signaturesequence, means for scrambling the one or more data layers and the oneor more preamble layers into a shared signal using the assigned eachsignature sequence, and means for transmitting the shared signal.

Another apparatus for wireless communications is described. Theapparatus may include a processor, memory in electronic communicationwith the processor, and instructions stored in the memory. Theinstructions may be operable to cause the processor to identify one ormore data layers and one or more preamble layers for transmission,determine a set of signature sequences for scrambling the one or moredata layers and the one or more preamble layers, assign each signaturesequence of the set of signature sequences to a data layer of the one ormore data layers or a preamble layer of the one or more preamble layersbased at least in part on a cross-correlation metric of the eachsignature sequence, scramble the one or more data layers and the one ormore preamble layers into a shared signal using the assigned eachsignature sequence, and transmit the shared signal.

A non-transitory computer-readable medium for wireless communications isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to identify one or more datalayers and one or more preamble layers for transmission, determine a setof signature sequences for scrambling the one or more data layers andthe one or more preamble layers, assign each signature sequence of theset of signature sequences to a data layer of the one or more datalayers or a preamble layer of the one or more preamble layers based atleast in part on a cross-correlation metric of the each signaturesequence, scramble the one or more data layers and the one or morepreamble layers into a shared signal using the assigned each signaturesequence, and transmit the shared signal.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, assigning the each signaturesequence of the set of signature sequences to the data layer of the oneor more data layers or the preamble layer of the one or more preamblelayers further includes assigning a first set of signature sequences ofthe set of signature sequences to the one or more data layers, the firstset of signature sequences corresponding to cross-correlation valuesthat may be lower than cross-correlation values of a second set ofsignature sequences of the set of signature sequences, and assigning thesecond set of signature sequences to the one or more preamble layers.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving a signature sequenceallocation message from a base station, where the set of signaturesequences may be determined according to the signature sequenceallocation message.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting the set of signaturesequences from a signature sequence pool, where the set of signaturesequences may be determined according to the selecting. In some examplesof the method, apparatus, and non-transitory computer-readable mediumdescribed above, the selecting the set of signature sequences from thesignature sequence pool may be based at least in part on a pseudo-randomselection procedure.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for assigning different modulationschemes, channel coding schemes, power allocations, or a combinationthereof to the one or more data layers, the one or more preamble layers,or a combination thereof. Some examples of the method, apparatus, andnon-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for dynamicallyconfiguring the modulation schemes, channel coding schemes, powerallocations, or the combination thereof each layer of the one or moredata layers, the one or more preamble layers, or the combinationthereof, where assigning the different modulation schemes, the channelcoding schemes, the power allocations, or the combination thereof may bebased at least in part on the dynamic configuration.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for assigning a same modulation scheme,channel coding scheme, power allocation, or a combination thereof to theone or more data layers, the one or more preamble layers, or acombination thereof.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, transmitting the shared signalincludes transmitting the shared signal using a Discrete FourierTransform-spread-orthogonal frequency division multiplexing (DFT-s-OFDM)waveform, a cyclic prefix-orthogonal frequency division multiplexing(CP-OFDM) waveform, or a combination thereof.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting one or moredemodulation reference signals (DMRSs) prior to transmitting the sharedsignal, where the one or more DMRSs include information for detectingthe shared signal. In other examples of the method, apparatus, andnon-transitory computer-readable medium described above, the sharedsignal includes a self-decodable signal.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, a preamble of the one or morepreamble layers includes a default value, a pre-determined sequence, apseudo-random sequence, or a combination thereof.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the set of signature sequencesincludes orthogonal signature sequences, non-orthogonal signaturesequences, or a combination thereof. In some examples of the method,apparatus, and non-transitory computer-readable medium described above,the shared signal includes a NOMA signal.

A method of wireless communications is described. The method may includereceiving a candidate signal from a UE, determining one or more preamblelayers scrambled in the candidate signal, and decoding one or more datalayers scrambled in the candidate signal based at least in part on theone or more preamble layers.

An apparatus for wireless communications is described. The apparatus mayinclude means for receiving a candidate signal from a UE, means fordetermining one or more preamble layers scrambled in the candidatesignal, and means for decoding one or more data layers scrambled in thecandidate signal based at least in part on the one or more preamblelayers.

Another apparatus for wireless communications is described. Theapparatus may include a processor, memory in electronic communicationwith the processor, and instructions stored in the memory. Theinstructions may be operable to cause the processor to receive acandidate signal from a UE, determine one or more preamble layersscrambled in the candidate signal, and decode one or more data layersscrambled in the candidate signal based at least in part on the one ormore preamble layers.

A non-transitory computer-readable medium for wireless communications isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to receive a candidate signalfrom a UE, determine one or more preamble layers scrambled in thecandidate signal, and decode one or more data layers scrambled in thecandidate signal based at least in part on the one or more preamblelayers.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for jointly decoding the one or morepreamble layers with the one or more data layers. In some examples ofthe method, apparatus, and non-transitory computer-readable mediumdescribed above, decoding the one or more data layers includesperforming a message-passing procedure, where the one or more preamblelayers may be used as prior information for the message-passingprocedure.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for performing channel estimation forthe candidate signal based at least in part on the one or more preamblelayers, where the one or more data layers may be decoded based at leastin part on the channel estimation. In some examples of the method,apparatus, and non-transitory computer-readable medium described above,performing the channel estimation for the candidate signal includescomparing the one or more preamble layers to one or more expectedpreamble values. In some examples of the method, apparatus, andnon-transitory computer-readable medium described above, a preamblevalue of the one or more expected preamble values includes a defaultvalue, a pre-determined sequence, a pseudo-random sequence, or acombination thereof.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting a signature sequenceallocation message to the UE, where the candidate signal received fromthe UE may be based at least in part on the signature sequenceallocation message. Some examples of the method, apparatus, andnon-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for determining aset of signature sequences, where the signature sequence allocationmessage indicates the set of signature sequences and where determiningthe one or more preamble layers scrambled in the candidate signal may bebased at least in part on the set of signature sequences.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for determining a set of signaturesequences for detecting the one or more data layers. Some examples ofthe method, apparatus, and non-transitory computer-readable mediumdescribed above may further include processes, features, means, orinstructions for descrambling the one or more data layers from thecandidate signal based at least in part on the set of signaturesequences, where decoding the one or more data layers scrambled in thecandidate signal may be based at least in part on the descrambling.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving one or more DMRSs for thecandidate signal. Some examples of the method, apparatus, andnon-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for performingchannel estimation for the candidate signal based at least in part onthe one or more DMRSs, where the one or more data layers may be decodedbased at least in part on the channel estimation.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for determining a set of signaturesequences for detecting the one or more preamble layers. Some examplesof the method, apparatus, and non-transitory computer-readable mediumdescribed above may further include processes, features, means, orinstructions for descrambling the one or more preamble layers from thecandidate signal based at least in part on the set of signaturesequences, where determining the one or more preamble layers scrambledin the candidate signal may be based at least in part on thedescrambling.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the candidate signal includesa self-decodable signal.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the candidate signal includesa NOMA signal. In some examples of the method, apparatus, andnon-transitory computer-readable medium described above, the candidatesignal includes a shared signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate examples of wireless communications systemsthat support parallel transmission of preamble sequences with datalayers for improved data detection in accordance with aspects of thepresent disclosure.

FIGS. 3 and 4 illustrate examples of signal generation processes thatsupport parallel transmission of preamble sequences with data layers forimproved data detection in accordance with aspects of the presentdisclosure.

FIG. 5 illustrates an example of a process flow that supports paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure.

FIGS. 6 through 8 show block diagrams of a device that supports paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure.

FIG. 9 illustrates a block diagram of a system including a userequipment (UE) that supports parallel transmission of preamble sequenceswith data layers for improved data detection in accordance with aspectsof the present disclosure.

FIGS. 10 through 12 show block diagrams of a device that supportsparallel transmission of preamble sequences with data layers forimproved data detection in accordance with aspects of the presentdisclosure.

FIG. 13 illustrates a block diagram of a system including a base stationthat supports parallel transmission of preamble sequences with datalayers for improved data detection in accordance with aspects of thepresent disclosure.

FIGS. 14 through 18 illustrate methods for parallel transmission ofpreamble sequences with data layers for improved data detection inaccordance with aspects of the present disclosure.

DETAILED DESCRIPTION

In some wireless communications systems (e.g., non-orthogonal multipleaccess (NOMA) or massive Internet of Things (IoT) systems), a basestation may provide uplink access to a large number of user equipments(UEs) within a given time frame (e.g., a transmission time interval(TTI), a slot). But the number of reference signals available for use byUEs in this time frame may be limited due to certain parameters orconstraints. Accordingly, to efficiently utilize the uplink accesscapabilities of the system, many UEs may transmit on the uplink withoutusing reference signals (e.g., demodulation reference signals (DMRSs)).In some cases, transmitting self-decodable signals (e.g., signalswithout corresponding reference signals) may result in reduceddetectability performance at the base station. To mitigate thisreduction in detectability and better support self-decodable signals, aUE may implement parallel transmission of preamble sequences with uplinkdata. In some cases, UEs may use these parallel transmissions along withreference signals for redundancy in detection performance.

To implement the parallel transmissions, a UE may identify uplink datafor transmission. The UE may split the uplink data into one or more datalayers (e.g., based on a target spectral efficiency), and may determineone or more preambles (as one example) to transmit along with the data.The preambles may be examples of default values, pre-determinedsequences, pseudo-random sequences, or some combination of these. A basestation receiving the signal may include an indication of the preamblesavailable to the UEs, such that the base station may identify preamblesreceived on the uplink.

In some examples, the data layers and the preamble layers may besuperposed. To superpose the data layers and the preamble layers, the UEmay determine a set of signature sequences. The UE may assign adifferent signature sequence to at least some of, if not each of, thecode layers (e.g., where every data layer and every preamble layers isassigned a different sequence), which may in some cases be based oncross-correlation values of the sequences. For example, the UE may splitthe set of signatures sequences into a first group of sequencescorresponding to a first set of cross-correlation values (e.g.,relatively lower cross-correlation values) and a second group ofsequences corresponding to a second set of cross-correlation values(e.g., relatively higher cross-correlation values), and may assign thefirst group of sequences to the data layers and the second group ofsequences to the preamble layers. In this way, the UE may improve thedetectability of the data layers due to the low cross-correlation valuesof their assigned signature sequences.

The UE may scramble the data layers and preamble layers using theassigned signature sequences, and may superpose the scrambled layersinto a shared signal. The UE may transmit this shared signal on theuplink to a base station. The base station may detect and decode theuplink data (e.g., based on the preamble layers). For example, in somecases, the base station may determine at least one preamble layer, andmay perform channel estimation based on the received preamble related tothe at least one preamble layer. In other cases, the base station mayjointly decode the data and preamble layers, and may use the preamblesas prior information for a message-passing procedure to decode theuplink data. The parallel transmission of the preambles with the datamay improve the data detection performance at the base station, allowingUEs to reliably transmit self-decodable uplink signals and efficientlyutilize the uplink access capabilities of a NOMA wireless system.

Aspects of the disclosure are initially described in the context ofwireless communications systems. Additional aspects of the disclosureare described with respect to signal generation process and processflows. Aspects of the disclosure are further illustrated by anddescribed with reference to apparatus diagrams, system diagrams, andflowcharts that relate to parallel transmission of preamble sequenceswith data layers for improved data detection.

FIG. 1 illustrates an example of a wireless communications system 100 inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, UEs 115, and acore network 130. In some examples, the wireless communications system100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A)network, an LTE-A Pro network, or a New Radio (NR) network. In somecases, wireless communications system 100 may support enhanced broadbandcommunications, ultra-reliable (e.g., mission critical) communications,low latency communications, or communications with low-cost andlow-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Base stations 105 described herein mayinclude or may be referred to by those skilled in the art as a basetransceiver station, a radio base station, an access point, a radiotransceiver, a NodeB, an eNodeB (eNB), a next-generation Node B orgiga-nodeB (either of which may be referred to as a gNB), a Home NodeB,a Home eNodeB, or some other suitable terminology. Wirelesscommunications system 100 may include base stations 105 of differenttypes (e.g., macro or small cell base stations). The UEs 115 describedherein may be able to communicate with various types of base stations105 and network equipment including macro eNBs, small cell eNBs, gNBs,relay base stations, and the like.

Each base station 105 may be associated with a particular geographiccoverage area 110 in which communications with various UEs 115 issupported. Each base station 105 may provide communication coverage fora respective geographic coverage area 110 via communication links 125,and communication links 125 between a base station 105 and a UE 115 mayutilize one or more carriers. Communication links 125 shown in wirelesscommunications system 100 may include uplink transmissions from a UE 115to a base station 105, or downlink transmissions from a base station 105to a UE 115. Downlink transmissions may also be called forward linktransmissions while uplink transmissions may also be called reverse linktransmissions.

The geographic coverage area 110 for a base station 105 may be dividedinto sectors making up only a portion of the geographic coverage area110, and each sector may be associated with a cell. For example, eachbase station 105 may provide communication coverage for a macro cell, asmall cell, a hot spot, or other types of cells, or various combinationsthereof. In some examples, a base station 105 may be movable andtherefore provide communication coverage for a moving geographiccoverage area 110. In some examples, different geographic coverage areas110 associated with different technologies may overlap, and overlappinggeographic coverage areas 110 associated with different technologies maybe supported by the same base station 105 or by different base stations105. The wireless communications system 100 may include, for example, aheterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different typesof base stations 105 provide coverage for various geographic coverageareas 110.

The term “cell” refers to a logical communication entity used forcommunication with a base station 105 (e.g., over a carrier), and may beassociated with an identifier for distinguishing neighboring cells(e.g., a physical cell identifier (PCID), a virtual cell identifier(VCID)) operating via the same or a different carrier. In some examples,a carrier may support multiple cells, and different cells may beconfigured according to different protocol types (e.g., machine-typecommunication (MTC), narrowband Internet-of-Things (NB-IoT), enhancedmobile broadband (eMBB), or others) that may provide access fordifferent types of devices. In some cases, the term “cell” may refer toa portion of a geographic coverage area 110 (e.g., a sector) over whichthe logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to as a mobile device, a wireless device, a remote device, ahandheld device, or a subscriber device, or some other suitableterminology, where the “device” may also be referred to as a unit, astation, a terminal, or a client. A UE 115 may also be a personalelectronic device such as a cellular phone, a personal digital assistant(PDA), a tablet computer, a laptop computer, or a personal computer. Insome examples, a UE 115 may also refer to a wireless local loop (WLL)station, an Internet of Things (IoT) device, an Internet of Everything(IoE) device, or an MTC device, or the like, which may be implemented invarious articles such as appliances, vehicles, meters, or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices, and may provide for automated communication betweenmachines (e.g., via Machine-to-Machine (M2M) communication). M2Mcommunication or MTC may refer to data communication technologies thatallow devices to communicate with one another or a base station 105without human intervention. In some examples, M2M communication or MTCmay include communications from devices that integrate sensors or metersto measure or capture information and relay that information to acentral server or application program that can make use of theinformation or present the information to humans interacting with theprogram or application. Some UEs 115 may be designed to collectinformation or enable automated behavior of machines. Examples ofapplications for MTC devices include smart metering, inventorymonitoring, water level monitoring, equipment monitoring, healthcaremonitoring, wildlife monitoring, weather and geological eventmonitoring, fleet management and tracking, remote security sensing,physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reducepower consumption, such as half-duplex communications (e.g., a mode thatsupports one-way communication via transmission or reception, but nottransmission and reception simultaneously). In some examples half-duplexcommunications may be performed at a reduced peak rate. Other powerconservation techniques for UEs 115 include entering a power saving“deep sleep” mode when not engaging in active communications, oroperating over a limited bandwidth (e.g., according to narrowbandcommunications). In some cases, UEs 115 may be designed to supportcritical functions (e.g., mission critical functions), and a wirelesscommunications system 100 may be configured to provide ultra-reliablecommunications for these functions.

In some cases, a UE 115 may also be able to communicate directly withother UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device(D2D) protocol). One or more of a group of UEs 115 utilizing D2Dcommunications may be within the geographic coverage area 110 of a basestation 105. Other UEs 115 in such a group may be outside the geographiccoverage area 110 of a base station 105, or be otherwise unable toreceive transmissions from a base station 105. In some cases, groups ofUEs 115 communicating via D2D communications may utilize a one-to-many(1:M) system in which each UE 115 transmits to every other UE 115 in thegroup. In some cases, a base station 105 facilitates the scheduling ofresources for D2D communications. In other cases, D2D communications arecarried out between UEs 115 without the involvement of a base station105.

Base stations 105 may communicate with the core network 130 and with oneanother. For example, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., via an S1 or otherinterface). Base stations 105 may communicate with one another overbackhaul links 134 (e.g., via an X2 or other interface) either directly(e.g., directly between base stations 105) or indirectly (e.g., via corenetwork 130).

The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. The core network 130 may be anevolved packet core (EPC), which may include at least one mobilitymanagement entity (MME), at least one serving gateway (S-GW), and atleast one Packet Data Network (PDN) gateway (P-GW). The MME may managenon-access stratum (e.g., control plane) functions such as mobility,authentication, and bearer management for UEs 115 served by basestations 105 associated with the EPC. User IP packets may be transferredthrough the S-GW, which itself may be connected to the P-GW. The P-GWmay provide IP address allocation as well as other functions. The P-GWmay be connected to the network operators IP services. The operators IPservices may include access to the Internet, Intranet(s), an IPMultimedia Subsystem (IMS), or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, mayinclude subcomponents such as an access network entity, which may be anexample of an access node controller (ANC). Each access network entitymay communicate with UEs 115 through a number of other access networktransmission entities, which may be referred to as a radio head, a smartradio head, or a transmission/reception point (TRP). In someconfigurations, various functions of each access network entity or basestation 105 may be distributed across various network devices (e.g.,radio heads and access network controllers) or consolidated into asingle network device (e.g., a base station 105).

Wireless communications system 100 may operate using one or morefrequency bands, typically in the range of 300 MHz to 300 GHz.Generally, the region from 300 MHz to 3 GHz is known as the ultra-highfrequency (UHF) region or decimeter band, since the wavelengths rangefrom approximately one decimeter to one meter in length. UHF waves maybe blocked or redirected by buildings and environmental features.However, the waves may penetrate structures sufficiently for a macrocell to provide service to UEs 115 located indoors. Transmission of UHFwaves may be associated with smaller antennas and shorter range (e.g.,less than 100 km) compared to transmission using the smaller frequenciesand longer waves of the high frequency (HF) or very high frequency (VHF)portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super highfrequency (SHF) region using frequency bands from 3 GHz to 30 GHz, alsoknown as the centimeter band. The SHF region includes bands such as the5 GHz industrial, scientific, and medical (ISM) bands, which may be usedopportunistically by devices that can tolerate interference from otherusers.

Wireless communications system 100 may also operate in an extremely highfrequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz),also known as the millimeter band. In some examples, wirelesscommunications system 100 may support millimeter wave (mmW)communications between UEs 115 and base stations 105, and EHF antennasof the respective devices may be even smaller and more closely spacedthan UHF antennas. In some cases, this may facilitate use of antennaarrays within a UE 115. However, the propagation of EHF transmissionsmay be subject to even greater atmospheric attenuation and shorter rangethan SHF or UHF transmissions. Techniques disclosed herein may beemployed across transmissions that use one or more different frequencyregions, and designated use of bands across these frequency regions maydiffer by country or regulating body.

In some cases, wireless communications system 100 may utilize bothlicensed and unlicensed radio frequency spectrum bands. For example,wireless communications system 100 may employ License Assisted Access(LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technologyin an unlicensed band such as the 5 GHz ISM band. When operating inunlicensed radio frequency spectrum bands, wireless devices such as basestations 105 and UEs 115 may employ listen-before-talk (LBT) proceduresto ensure a frequency channel is clear before transmitting data. In somecases, operations in unlicensed bands may be based on a CA configurationin conjunction with CCs operating in a licensed band (e.g., LAA).Operations in unlicensed spectrum may include downlink transmissions,uplink transmissions, peer-to-peer transmissions, or a combination ofthese. Duplexing in unlicensed spectrum may be based on frequencydivision duplexing (FDD), time division duplexing (TDD), or acombination of both.

In some examples, base station 105 or UE 115 may be equipped withmultiple antennas, which may be used to employ techniques such astransmit diversity, receive diversity, multiple-input multiple-output(MIMO) communications, or beamforming. For example, wirelesscommunications system 100 may use a transmission scheme between atransmitting device (e.g., a base station 105) and a receiving device(e.g., a UE 115), where the transmitting device is equipped withmultiple antennas and the receiving devices are equipped with one ormore antennas. MIMO communications may employ multipath signalpropagation to increase the spectral efficiency by transmitting orreceiving multiple signals via different spatial layers, which may bereferred to as spatial multiplexing. The multiple signals may, forexample, be transmitted by the transmitting device via differentantennas or different combinations of antennas. Likewise, the multiplesignals may be received by the receiving device via different antennasor different combinations of antennas. Each of the multiple signals maybe referred to as a separate spatial stream, and may carry bitsassociated with the same data stream (e.g., the same codeword) ordifferent data streams. Different spatial layers may be associated withdifferent antenna ports used for channel measurement and reporting. MIMOtechniques include single-user MIMO (SU-MIMO) where multiple spatiallayers are transmitted to the same receiving device, and multiple-userMIMO (MU-MIMO) where multiple spatial layers are transmitted to multipledevices.

Beamforming, which may also be referred to as spatial filtering,directional transmission, or directional reception, is a signalprocessing technique that may be used at a transmitting device or areceiving device (e.g., a base station 105 or a UE 115) to shape orsteer an antenna beam (e.g., a transmit beam or receive beam) along aspatial path between the transmitting device and the receiving device.Beamforming may be achieved by combining the signals communicated viaantenna elements of an antenna array such that signals propagating atparticular orientations with respect to an antenna array experienceconstructive interference while others experience destructiveinterference. The adjustment of signals communicated via the antennaelements may include a transmitting device or a receiving deviceapplying certain amplitude and phase offsets to signals carried via eachof the antenna elements associated with the device. The adjustmentsassociated with each of the antenna elements may be defined by abeamforming weight set associated with a particular orientation (e.g.,with respect to the antenna array of the transmitting device orreceiving device, or with respect to some other orientation).

In one example, a base station 105 may use multiple antennas or antennaarrays to conduct beamforming operations for directional communicationswith a UE 115. For instance, some signals (e.g. synchronization signals,reference signals, beam selection signals, or other control signals) maybe transmitted by a base station 105 multiple times in differentdirections, which may include a signal being transmitted according todifferent beamforming weight sets associated with different directionsof transmission. Transmissions in different beam directions may be usedto identify (e.g., by the base station 105 or a receiving device, suchas a UE 115) a beam direction for subsequent transmission and/orreception by the base station 105. Some signals, such as data signalsassociated with a particular receiving device, may be transmitted by abase station 105 in a single beam direction (e.g., a directionassociated with the receiving device, such as a UE 115). In someexamples, the beam direction associated with transmissions along asingle beam direction may be determined based at least in in part on asignal that was transmitted in different beam directions. For example, aUE 115 may receive one or more of the signals transmitted by the basestation 105 in different directions, and the UE 115 may report to thebase station 105 an indication of the received signal with a highestsignal quality, or an otherwise acceptable signal quality. Althoughthese techniques are described with reference to signals transmitted inone or more directions by a base station 105, a UE 115 may employsimilar techniques for transmitting signals multiple times in differentdirections (e.g., for identifying a beam direction for subsequenttransmission or reception by the UE 115), or transmitting a signal in asingle direction (e.g., for transmitting data to a receiving device).

A receiving device (e.g., a UE 115, which may be an example of a mmWreceiving device) may try multiple receive beams when receiving varioussignals from the base station 105, such as synchronization signals,reference signals, beam selection signals, or other control signals. Forexample, a receiving device may try multiple receive directions byreceiving via different antenna subarrays, by processing receivedsignals according to different antenna subarrays, by receiving accordingto different receive beamforming weight sets applied to signals receivedat a plurality of antenna elements of an antenna array, or by processingreceived signals according to different receive beamforming weight setsapplied to signals received at a plurality of antenna elements of anantenna array, any of which may be referred to as “listening” accordingto different receive beams or receive directions. In some examples areceiving device may use a single receive beam to receive along a singlebeam direction (e.g., when receiving a data signal). The single receivebeam may be aligned in a beam direction determined based at least inpart on listening according to different receive beam directions (e.g.,a beam direction determined to have a highest signal strength, highestsignal-to-noise ratio, or otherwise acceptable signal quality based atleast in part on listening according to multiple beam directions).

In some cases, the antennas of a base station 105 or UE 115 may belocated within one or more antenna arrays, which may support MIMOoperations, or transmit or receive beamforming. For example, one or morebase station antennas or antenna arrays may be co-located at an antennaassembly, such as an antenna tower. In some cases, antennas or antennaarrays associated with a base station 105 may be located in diversegeographic locations. A base station 105 may have an antenna array witha number of rows and columns of antenna ports that the base station 105may use to support beamforming of communications with a UE 115.Likewise, a UE 115 may have one or more antenna arrays that may supportvarious MIMO or beamforming operations.

In some cases, wireless communications system 100 may be a packet-basednetwork that operate according to a layered protocol stack. In the userplane, communications at the bearer or Packet Data Convergence Protocol(PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may insome cases perform packet segmentation and reassembly to communicateover logical channels. A Medium Access Control (MAC) layer may performpriority handling and multiplexing of logical channels into transportchannels. The MAC layer may also use hybrid automatic repeat request(HARQ) to provide retransmission at the MAC layer to improve linkefficiency. In the control plane, the Radio Resource Control (RRC)protocol layer may provide establishment, configuration, and maintenanceof an RRC connection between a UE 115 and a base station 105 or corenetwork 130 supporting radio bearers for user plane data. At thePhysical (PHY) layer, transport channels may be mapped to physicalchannels.

In some cases, UEs 115 and base stations 105 may support retransmissionsof data to increase the likelihood that data is received successfully.HARQ feedback is one technique of increasing the likelihood that data isreceived correctly over a communication link 125. HARQ may include acombination of error detection (e.g., using a cyclic redundancy check(CRC)), forward error correction (FEC), and retransmission (e.g.,automatic repeat request (ARQ)). HARQ may improve throughput at the MAClayer in poor radio conditions (e.g., signal-to-noise conditions). Insome cases, a wireless device may support same-slot HARQ feedback, wherethe device may provide HARQ feedback in a specific slot for datareceived in a previous symbol in the slot. In other cases, the devicemay provide HARQ feedback in a subsequent slot, or according to someother time interval.

Time intervals in LTE or NR may be expressed in multiples of a basictime unit, which may, for example, refer to a sampling period ofTs=1/30,720,000 seconds. Time intervals of a communications resource maybe organized according to radio frames each having a duration of 10milliseconds (ms), where the frame period may be expressed as Tf=307,200Ts. The radio frames may be identified by a system frame number (SFN)ranging from 0 to 1023. Each frame may include 10 subframes numberedfrom 0 to 9, and each subframe may have a duration of 1 ms. A subframemay be further divided into 2 slots each having a duration of 0.5 ms,and each slot may contain 6 or 7 modulation symbol periods (e.g.,depending on the length of the cyclic prefix prepended to each symbolperiod). Excluding the cyclic prefix, each symbol period may contain2048 sampling periods. In some cases, a subframe may be the smallestscheduling unit of the wireless communications system 100, and may bereferred to as a transmission time interval (TTI). In other cases, asmallest scheduling unit of the wireless communications system 100 maybe shorter than a subframe or may be dynamically selected (e.g., inbursts of shortened TTIs (sTTIs) or in selected component carriers usingsTTIs).

In some wireless communications systems, a slot may further be dividedinto multiple mini-slots containing one or more symbols. In someinstances, a symbol of a mini-slot or a mini-slot may be the smallestunit of scheduling. Each symbol may vary in duration depending on thesubcarrier spacing or frequency band of operation, for example. Further,some wireless communications systems may implement slot aggregation inwhich multiple slots or mini-slots are aggregated together and used forcommunication between a UE 115 and a base station 105.

The term “carrier” refers to a set of radio frequency spectrum resourceshaving a defined physical layer structure for supporting communicationsover a communication link 125. For example, a carrier of a communicationlink 125 may include a portion of a radio frequency spectrum band thatis operated according to physical layer channels for a given radioaccess technology. Each physical layer channel may carry user data,control information, or other signaling. A carrier may be associatedwith a pre-defined frequency channel (e.g., an E-UTRA absolute radiofrequency channel number (EARFCN)), and may be positioned according to achannel raster for discovery by UEs 115. Carriers may be downlink oruplink (e.g., in an FDD mode), or be configured to carry downlink anduplink communications (e.g., in a TDD mode). In some examples, signalwaveforms transmitted over a carrier may be made up of multiplesub-carriers (e.g., using multi-carrier modulation (MCM) techniques suchas orthogonal frequency division multiplexing (OFDM) or DFT-s-OFDM).

The organizational structure of the carriers may be different fordifferent radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR).For example, communications over a carrier may be organized according toTTIs or slots, each of which may include user data as well as controlinformation or signaling to support decoding the user data. A carriermay also include dedicated acquisition signaling (e.g., synchronizationsignals or system information) and control signaling that coordinatesoperation for the carrier. In some examples (e.g., in a carrieraggregation configuration), a carrier may also have acquisitionsignaling or control signaling that coordinates operations for othercarriers.

Physical channels may be multiplexed on a carrier according to varioustechniques. A physical control channel and a physical data channel maybe multiplexed on a downlink carrier, for example, using time divisionmultiplexing (TDM) techniques, frequency division multiplexing (FDM)techniques, or hybrid TDM-FDM techniques. In some examples, controlinformation transmitted in a physical control channel may be distributedbetween different control regions in a cascaded manner (e.g., between acommon control region or common search space and one or more UE-specificcontrol regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radiofrequency spectrum, and in some examples the carrier bandwidth may bereferred to as a “system bandwidth” of the carrier or the wirelesscommunications system 100. For example, the carrier bandwidth may be oneof a number of predetermined bandwidths for carriers of a particularradio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). Insome examples, each served UE 115 may be configured for operating overportions or all of the carrier bandwidth. In other examples, some UEs115 may be configured for operation using a narrowband protocol typethat is associated with a predefined portion or range (e.g., set ofsubcarriers or RBs) within a carrier (e.g., “in-band” deployment of anarrowband protocol type).

In a system employing MCM techniques, a resource element may consist ofone symbol period (e.g., a duration of one modulation symbol) and onesubcarrier, where the symbol period and subcarrier spacing are inverselyrelated. The number of bits carried by each resource element may dependon the modulation scheme (e.g., the order of the modulation scheme).Thus, the more resource elements that a UE 115 receives and the higherthe order of the modulation scheme, the higher the data rate may be forthe UE 115. In MIMO systems, a wireless communications resource mayrefer to a combination of a radio frequency spectrum resource, a timeresource, and a spatial resource (e.g., spatial layers), and the use ofmultiple spatial layers may further increase the data rate forcommunications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations105 or UEs 115) may have a hardware configuration that supportscommunications over a particular carrier bandwidth, or may beconfigurable to support communications over one of a set of carrierbandwidths. In some examples, the wireless communications system 100 mayinclude base stations 105 and/or UEs that can support simultaneouscommunications via carriers associated with more than one differentcarrier bandwidth.

Wireless communications system 100 may support communication with a UE115 on multiple cells or carriers, a feature which may be referred to ascarrier aggregation (CA) or multi-carrier operation. A UE 115 may beconfigured with multiple downlink CCs and one or more uplink CCsaccording to a carrier aggregation configuration. Carrier aggregationmay be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers (eCCs). An eCC may be characterized by one or morefeatures including wider carrier or frequency channel bandwidth, shortersymbol duration, shorter TTI duration, or modified control channelconfiguration. In some cases, an eCC may be associated with a carrieraggregation configuration or a dual connectivity configuration (e.g.,when multiple serving cells have a suboptimal or non-ideal backhaullink). An eCC may also be configured for use in unlicensed spectrum orshared spectrum (e.g., where more than one operator is allowed to usethe spectrum). An eCC characterized by wide carrier bandwidth mayinclude one or more segments that may be utilized by UEs 115 that arenot capable of monitoring the whole carrier bandwidth or are otherwiseconfigured to use a limited carrier bandwidth (e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than otherCCs, which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration may beassociated with increased spacing between adjacent subcarriers. Adevice, such as a UE 115 or base station 105, utilizing eCCs maytransmit wideband signals (e.g., according to frequency channel orcarrier bandwidths of 20, 40, 60, 80 MHz) at reduced symbol durations(e.g., 16.67 microseconds). A TTI in eCC may consist of one or multiplesymbol periods. In some cases, the TTI duration (that is, the number ofsymbol periods in a TTI) may be variable.

Wireless communications systems such as an NR system may utilize anycombination of licensed, shared, and unlicensed spectrum bands, amongothers. The flexibility of eCC symbol duration and subcarrier spacingmay allow for the use of eCC across multiple spectrums. In someexamples, NR shared spectrum may increase spectrum utilization andspectral efficiency, specifically through dynamic vertical (e.g., acrossfrequency) and horizontal (e.g., across time) sharing of resources.

In some wireless communications systems 100 (e.g., NOMA or massive IoTsystems), a base station 105 may provide uplink access to a large numberof UEs 115 within a given time frame (e.g., a TTI, a slot). The numberof reference signals available for use by UEs 115 in this time frame,however, may be limited. Accordingly, to efficiently utilize the uplinkaccess capabilities of the system, many UEs 115 may transmit on theuplink without using reference signals (e.g., DMRSs). Transmittingself-decodable signals (e.g., signals without corresponding referencesignals) may result in a reduction in detectability performance at thebase station 105. To improve this detectability performance and bettersupport these self-decodable signals, a UE 115 may implement paralleltransmission (e.g., concurrent transmission) of preamble sequences withuplink data. In some cases, the UE 115 may use these paralleltransmissions along with reference signals for additional redundancy.

To implement the parallel transmissions, a UE 115 may identify uplinkdata for transmission. The UE 115 may allocate the uplink data amongstone or more data layers (e.g., based on a desired spectral efficiency),and may determine one or more preambles to transmit along with the data.The preambles may be examples of default values, pre-determinedsequences, pseudo-random sequences, or some combination of these, amongother possibilities. The base station 105 may include an indication ofthe preambles available to the UEs 115, such that the base station 105may identify any preambles received in an uplink signal. To superposethe data layers and the preamble layers, the UE 115 may determine a setof signature sequences. The UE 115 may assign a different signaturesequence to each code layer (e.g., where every data layer and everypreamble layers is assigned a different sequence) or using a differentmapping to one or more code layers based on cross-correlation values ofthe sequences. For example, the UE 115 may split the set of signaturessequences into a first group of sequences corresponding to relativelylower cross-correlation values and a second group of sequencescorresponding to relatively higher cross-correlation values, and mayassign the first group of sequences to the data layers and the secondgroup of sequences to the preamble layers. In this way, the UE 115 mayimprove the detectability of the data layers due to the lowcross-correlation values of the assigned signature sequences.

The UE 115 may scramble the data layers and preamble layers using theassigned signature sequences, and may superpose the scrambled layersinto a shared signal. The UE 115 may transmit the shared signal on theuplink to a base station 105. The base station 105 may detect and decodethe uplink data based on the preamble layers. For example, in somecases, the base station 105 may determine at least one preamble layer,and may perform channel estimation based on the received preamble. Inother cases, the base station 105 may jointly decode the data andpreamble layers, and may use the preambles as prior information for amessage-passing procedure to decode the uplink data. The paralleltransmission of the preambles with the data may improve the datadetection performance at the base station 105, allowing UEs 115 toreliably transmit self-decodable uplink signals.

FIG. 2 illustrates an example of a wireless communications system 200that supports parallel transmission of preamble sequences with datalayers for improved data detection in accordance with various aspects ofthe present disclosure. The wireless communications system 200 mayinclude base station 105-a and UE 115-a, which may be examples of a basestation 105 and a UE 115 respectively, as described with reference toFIG. 1. Base station 105-a may serve UEs 115 within a geographic area110-a, including UE 115-a, which may transmit on the uplink 205 to basestation 105-a within a NOMA wireless system. In some cases, UE 115-a mayimplement parallel transmissions of one or more data layers 215 and oneor more preamble layers 220 within a signal 210 for improved datadetection at base station 105-a.

In some wireless systems (e.g., NOMA systems), base station 105-a mayprovide uplink access to a large number of UEs 115 at the same time(e.g., simultaneously, during a same TTI,) within a certain geographicarea 110. For example, the wireless communications system 200 may be anexample of a massive IoT system, as one case, and may correspondinglysupport one millions UEs 115 per square kilometer (km) on the uplink 205in some implementations. A large number of or each of these UEs 115 may,in some cases, transmit data on the uplink 205 in one or more datastreams. A subset of the UEs 115 may transmit one or more referencesignals (e.g., DMRSs) with the uplink data for channel estimation, andbase station 105-a may reliably detect and receive these datatransmissions based on the reference signals. In a NOMA system, however,base station 105-a may support uplink access for a larger number of UEs115 than the number of available reference signals. Accordingly, anumber of UEs 115 may transmit self-decodable data transmissions on theuplink 205 (e.g., data transmitted independent of any correspondingreference signals). To improve detection of such data, UEs 115 mayimplement parallel transmission of at least some additional information,which may include one or more preambles, with the data transmission.This additional information (e.g., preamble) may be used by base station105-a for channel estimation (e.g., similar to a reference signal), orfor joint decoding, or both. In some cases, UEs 115 may implementparallel preamble transmissions in addition to reference signaltransmissions to add redundancy to the channel estimation procedure,improving the detection performance without negatively affecting thespectrum efficiency.

To implement the parallel transmission, UE 115-a may identify data totransmit on the uplink 205. UE 115-a may separate the data into one ormore data layers 215 for transmission. Each data layer 215 may be anexample of a code layer or sub-code layer corresponding to a differentsignature sequence 225. UE 115-a may additionally determine a number ofpreambles to transmit, where each preamble may be transmitted in adifferent preamble layer 220. Each preamble may, in some cases, be anexample of a value or sequence known by the base station 105-a. Forexample, the preamble may be an example of a pre-determined value orsequence, a frozen bit sequence (e.g., with all bits set to a frozen bitvalue, such as “0”), a known training sequence, a pseudo-random value orsequence, or some combination of these or similar values or sequences.Base station 105-a may store in memory one or more potential preamblesfor detection. In this way, if base station 105-a identifies a knownpreamble in a signal candidate, the base station 105-a may determinethat the signal candidate corresponds to an uplink signal 210 includingone or more data layers 215, and may improve detection of the datalayers 215 based on decoding one or more preamble layers 220.

To transmit the data layers 215 and preamble layers 220 together in ashared signal 210 (e.g., without reducing the spectral efficiency), UE115-a may assign different signature sequences 225 to various codelayers (e.g., each code layer). For example, UE 115-a may assignsignature sequence 225-a to data layer 215, and may assign signaturesequence 225-b to preamble layer 220. UE 115-a may then scramble thelayers using the assigned signature sequences, and may superpose thescrambled layers into a single signal 210. By utilizing at least somedifferent signature sequences 225 for the different layers, base station105-a at the receiver-side may separate the code layers according to thesignature sequences 225 to determine the preambles and the uplink data,and use the information appropriately.

In some cases, UE 115-a may assign the signature sequences 225 to thedifferent layers based on cross-correlation metrics for the signaturesequences 225. For example, UE 115-a may determine a number code layersfor transmission (e.g., including one or more data layers 215 and one ormore preamble layers 220), and may identify a number of signaturesequences 225 equal to the number of code layers. UE 115-a may identifycross-correlation values for each of these signature sequences 225. Insome cases, the cross-correlation values may be calculated using across-correlation function. In other cases, these cross-correlationvalues may be binary values indicating a relative cross correlation(e.g., a relatively high cross-correlation, a relatively lowcross-correlation) compared to the other selected signature sequences225. UE 115-a may assign the signature sequences 225 corresponding tothe lower cross-correlation values to the data layers 215, and mayassign the signature sequences 225 corresponding to the highercross-correlation values to the preamble layers 220. In some cases, UE115-a may identify one or more data layers 215 containing certain data(e.g., high priority data), and may assign the signature sequences 225with the lowest cross-correlation values to these identified highpriority data layers 215. As illustrated, signature sequence 225-a mayhave a lower cross-correlation value or metric than signature sequence225-b. By assigning signature sequences 225 based on cross-correlationmetrics, UE 115-a may improve the detection reliability of the data.

Base station 105-a receiving the signal 210 may detect the data layers215 based on the preamble layers 220. For example, in a NOMA system,base station 105-a may not schedule UE 115-a for uplink transmission.Instead, base station 105-a may monitor the channel for signals 210, andmay decode the associated data upon detecting a signal 210. For example,base station 105-a may detect a candidate signal. In some cases, basestation 105-a may decode one or more preamble layers 220, and mayidentify that the candidate signal corresponds to an uplink signal 210based on the preamble layers 220. Base station 105-a may include anindication (e.g., a table in memory, a preamble generation function) ofpotential preambles, and may monitor for these preambles scrambled in anuplink signal 210. Additionally or alternatively, base station 105-a maycontain an indication of potential sequences used by UE 115-a, and mayattempt to descramble (e.g., unscramble), the code layers using thesesignature sequences 225. When base station 105-a detects a signal 210,base station 105-a may in some cases perform channel estimation usingthe received preamble layers 220, and may decode the data layers 215based on the channel estimation.

In other cases, base station 105-a may utilize an advanced receiver(e.g., a message-passing receiver) for receiving and jointly decodingthe different coding layers. For example, base station 105-a may jointlydecode one or more preamble layers 220 and one or more data layers 215using the receiver. In some cases, the receiver may use one or moredecoded preamble layers 220 as prior information for a message-passingprocedure to decode the data layers 215. For self-decodable signals 210,base station 105-a may decode the data layers 215 using the preamblelayers 220 in place of reference signals. For signals 210 transmittedwith corresponding reference signals (e.g., DMRSs), base station 105-amay decode the data layers 215 using the preamble layers 220 in additionto the reference signals.

FIG. 3 illustrates an example of a signal generation process 300including a single data stream and a single preamble that supportsparallel transmission of preamble sequences with data layers forimproved data detection in accordance with various aspects of thepresent disclosure. The signal generation process 300 may be performedby a UE 115 as described with reference to FIGS. 1 and 2. The signalgeneration process 300 may involve at least one data layer 305 andpreamble layer 310. These layers may be scrambled (e.g., based onscrambling processes 330) according to different signature sequences325, and may be superposed onto a shared signal according to asuperposition process 345. The UE 115 may transmit this superposedsignal using an antenna 355. In some cases, the signal generationprocess 300 may include additional processes, such as channel coding315, modulation 320, power allocation 340, waveform generation 350, orsome combination of these or other signal generation procedures.

A UE 115 may identify the data layer 305 and preamble 310 fortransmission. For example, the UE 115 may identify data queued in a databuffer for uplink transmission, and may assign the data to a single datalayer 305. The UE 115 may determine the preamble 310 using apseudo-random selection process. In some cases, the UE 115 may selectthe preamble 310 from a list of possible preambles 310, or may determinethe preamble 310 using a preamble generation function (e.g., based on adynamic or configured input value for the preamble generation function).

In some systems, the UE 115 may perform processes or modifications onthese code layers. For example, the UE 115 may perform channel coding315, modulation 320, or both on one or more of the code layers. Channelcoding 315 may involve the UE 115 adding bits or sequences of bits tothe code layer to increase redundancy or reduce the error rate. Theseadded bits may involve parity check bits, cyclic redundancy check (CRC)bits, convolutional codes, or some combination of these or other bitsassociated with channel coding 315 techniques. Modulation 320 mayinvolve encoding the bits (e.g., the data or preamble bits combined withany error correction bits) onto a carrier signal using one or moremodulation techniques. In some cases, the channel coding 315 andmodulation 320 techniques implemented for each code layer may be thesame. In other cases, the UE 115 may utilize different techniques fordifferent code layers. For example, the UE 115 may implement channelcoding 315-a and modulation 320-a to modify the data layer 305, whileimplementing different channel coding 315-b, modulation 320-b, or bothto modify the preamble layer 310. In some cases, the UE 115 may utilizedifferent channel coding 315, modulation 320, or a combination of thesefor each code layer. In other cases, the UE 115 may utilize a firstchannel coding 315-a, modulation 320-a, or both for all data layers 305,and a second channel coding 315-b, modulation 320-b, or both for allpreamble layers 310.

The UE 115 may then scramble the signals using signature sequences 325.In some cases, a base station 105 may allocate the signature sequences325 for a UE 115 to use. For example, in a grant-based procedure, thebase station 105 may transmit a signature sequence grant to the UE 115,and the UE 115 may determine the signature sequences 325 to use forscrambling based on the grant. In other cases (e.g., in a grant-freeprocedure), the UE 115 may determine the signature sequences 325 withoutinput from the base station 105. For example, the UE 115 may select thesignature sequences 325 from one or more sequence pools (e.g., using apseudo-random selection procedure). The selected signature sequences 325may or may not be orthogonal. For example, even in a NOMA system,certain combinations of signature sequences 325 may be orthogonal,although most of the signature sequences 325 may not be orthogonal. TheUE 115 may assign the signature sequences 325 to the different codelayers for scrambling. Each code layer may utilize a different signaturesequence 325 for scrambling or spreading. The different signaturesequences 325 may define the different code layers. For example,applying the different signature sequences 325 to different bits orsignals may split the information into the multiple code layers.

The UE 115 may implement a same scrambling process 330 for each of thecode layers, or may implement different scrambling processes 330 (e.g.,scrambling process 330-a for data layer 305 and scrambling process 330-bfor preamble layer 310) for different code layers. In either case, theUE 115 may utilize different signature sequences 325 for the scramblingprocesses 330. For example, the UE 115 may assign signature sequence325-a to the data layer 305 and may assign signature sequence 325-b tothe preamble layer 310, and may scramble each layer using the assignedsignature sequence 325.

In some cases, the UE 115 may perform power allocation 340 for thescrambled signals. These power allocation 340 processes may utilize thesame or different power allocation 340 operations or functions (e.g.,power allocation 340-a for the data layer 305 and power allocation 340-bfor the preamble layer 310). Additionally, the UE 115 may apply the sameor different power allocation values 335 to these power allocation 340processes. In some cases, the UE 115 may dynamically configure thesepower allocation values 335 for each layer (e.g., configuring powerallocation value 335-a for the data layer 305 and power allocation value335-b for the preamble layer 310). In some examples, a base station 105may use different power allocation values 335 (e.g., for different codelayers at a UE 115 or for different UEs 115) to differentiate betweenlayers or UEs 115.

The UE 115 may superpose the resulting signals into a shared signal(e.g., based on a superposition process 345). In some cases, the UE 115may fit the shared signal to a waveform 350 (e.g., a Discrete FourierTransform-spread-orthogonal frequency division multiplexing (DFT-s-OFDM)waveform, a cyclic prefix-orthogonal frequency division multiplexing(CP-OFDM) waveform, or some combination of these or other waveforms).The UE 115 may send the resulting signal or waveform to an antenna 355for transmission to a base station 105. The base station 105 may receivethe transmitted signal with an improved detection performance based onthe superposed preamble layer 310.

FIG. 4 illustrates an example of a signal generation process 400including multiple data streams and preambles that supports paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with various aspects of the present disclosure.The signal generation process 400 may be performed by a UE 115 asdescribed with reference to FIGS. 1 through 3. The signal generationprocess 400 may be an extension of the signal generation process 300,involving multiple data streams 405 and preambles 410 (e.g., k datastreams 405 and n preambles 410).

These layers may all be scrambled according to different signaturesequences and superposed into a single shared signal for transmission.Involving a greater number of code layers may polarize thecross-correlation values for the signature sequences. For example, inthe signal generation process 300 including a single data stream and asingle preamble, the signature sequences may have the samecross-correlation values, as only two sequences are used. However, insignal generation process 400 including n+k code layers and,correspondingly, n+k signature sequences, different sequences may havedifferent cross-correlation values within the sequence set.

The UE 115 may identify k data streams 405 for transmission within ashared signal. In some cases, the UE 115 may determine the number ofdata layers to implement based on an amount of uplink data, a targetspectral efficiency for the uplink data, or a combination thereof.Similarly, the UE 115 may identify n preambles 410 for transmissionparallel to the k data streams 405, resulting in a total number of codelayers k+n. The signal generation process 400 may include similarprocesses to those described above, for example, with respect to FIG. 3.For example, the UE 115 may perform channel coding 415, modulation 420,scrambling or spreading 425, power allocation 430, superposition 435,waveform generation 440, or any combination of these signal generationprocedures before transmitting the shared signal using an antenna 445.

These processes may be performed differently for different code layers,or may be applied universally (e.g., uniformly). For example, in onespecific case, the UE 115 may utilize a same channel coding 415 andmodulation 420 procedure for all of the code layers, but may utilizedifferent power allocation values, g, for the power allocation 430. Forexample, the UE 115 may determine power allocation values g1, g2, . . .g(k+n) corresponding to each code layer, where the power is splitunevenly between the data streams 405 and the preambles 410. Forexample, the UE 115 may utilize ⅔ of the available power for thepreambles 410, and the remaining ⅓ of the power for the data streams405. Alternatively, the UE 115 may split the power evenly between eachcode layer, or may split the power evenly between data power andpreamble power. In some cases, the UE 115 may further split theallocated power for different data streams 405 or different preambles410 unevenly. In other cases, each data stream 405 may use a powerallocation value equal to 1/k the allocated data power, and eachpreamble 410 may use a power allocation value equal to 1/n the allocatedpreamble power. The UE 115 may determine the power allocation staticallyor dynamically (e.g., on a layer-by-layer basis). In some examples, abase station 105 may transmit an indication of power allocationprocedures for the UE 115. In other examples, the UE 115 may determinepower allocation values based on received signal-to-noise ratio (SNR)measurements.

Additionally or alternatively, the UE 115 may assign differentsignatures sequences to the different code layers based oncross-correlation metrics of the signature sequences. For example, theUE 115 may determine a set of k+n signature sequences (e.g., based on agrant-based or grant-free procedure) to perform the parallelization ofthe code layers. The UE 115 may determine cross-correlation metrics foreach signature sequence of this set of signature sequences (e.g., basedon a lookup table in memory, a cross-correlation equation, groupings ofthe signature sequences). In some cases, these cross-correlation metricsmay be examples of absolute metrics (e.g., values between 0 and 1). TheUE 115 may order the signature sequences by cross-correlation metric,and may assign the signature sequences with lower cross-correlationmetrics to the data streams 405.

In some cases, the UE 115 may assign the lowest cross-correlation metricto data stream 405-a, the second lowest to data stream 405-b, etc. Inother cases, the UE 115 may determine the k lowest cross-correlationmetrics, and may assign the corresponding k signature sequencespseudo-randomly to the k data streams. The UE 115 may perform similarprocedures to assign the n signature sequences with the n highestcross-correlation metrics to the n preambles 410. As lowercross-correlation values may correspond to better detection performance,the UE 115 may distribute the signature sequences in this way to improvedata detection reliability at a receiving base station 105. Because thepreambles 410 are used to improve data detection, but do not carry anyuplink data themselves, applying the signature sequences with worsedetection performance to these preambles 410 may not negatively affectuplink data throughput.

FIG. 5 illustrates a process flow 500 that supports paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with various aspects of the present disclosure.Process flow 500 may include UE 115-b and base station 105-b, which maybe examples of the corresponding devices as described with reference toFIGS. 1 through 4. UE 115-b may transmit a signal to base station 105-bthat includes superposed data and preamble layers for improved detectionof the uplink data. In some implementations, the processes describedbelow may be performed in a different order, or may include one or moreadditional or alternative processes performed by UE 115-b, base station105-b, or both.

At 505, UE 115-b may identify one or more data layers and one or morepreamble layers for transmission. The preamble layers may function asreference signals for the data layers for improved detectability at abase station 105 (e.g., base station 105-b). The preambles at eachpreamble layer—or, in some cases, spread across multiple preamblelayers—may be examples of default values, pre-determined sequences,pseudo-random sequences, or some combination of these. Both UE 115-b andbase station 105-b may include indications of the preambles to be usedfor parallel transmissions.

At 510, UE 115-b may determine a set of signature sequences forscrambling the layers. In some cases (e.g., when operating in agrant-based system), UE 115-b may receive a signature sequenceallocation message from base station 105-b indicating the signaturesequences to use. In other cases (e.g., when operating in a grant-freesystem), UE 115-b may select the signatures sequences without anyexplicit or designated signaling, for example, using one or moresequence pools, one or more lookup tables, one or more sequencegeneration functions, etc. The set of signature sequences may include anumber of sequences equal to the number of layers for transmission(e.g., including both the data layers and preamble layers). Thesesignature sequences may be examples of NOMA signature sequences and, assuch, may include orthogonal signature sequences, non-orthogonalsignature sequences, or a combination of both.

At 515, UE 115-b may assign a different signature sequence to each codelayer. For example, based on the assignments, every signature sequenceof the set of signature sequences may correspond to one data layer ofthe one or more data layers or one preamble layer of the one or morepreamble layers. In some cases, the assigning of signature sequences maybe based on cross-correlation metrics of each signature sequence. Forexample, UE 115-b may assign a first set of signature sequences withrelatively lower cross-correlation values to the data layers, and mayassign a second set of signature sequences with relatively highercross-correlation values to the preamble layers.

At 520, UE 115-b may scramble the one or more data layers and the one ormore preamble layers into a shared signal using the assigned signaturesequences. In some cases, UE 115-b may perform additional signalmodification procedures to the layers before or after the scrambling.For example, UE 115-b may perform modulation, channel coding, powerallocation, or some combination of these processes on the data layers,preamble layers, or both. UE 115-b may either assign the same modulationschemes, channel coding schemes, and power allocation values to thedifferent layers or layer groups, or may assign different modulationschemes, channel coding schemes, or power allocation values to theselayers.

At 525, UE 115-b may transmit the shared signal to base station 105-b.In some cases, UE 115-b may transmit this shared signal withcorresponding reference signals (e.g., DMRSs) to aid in decoding. Inother cases, UE 115-b may transmit this shared signal withoutcorresponding reference signals (e.g., as a self-decodable signal). Theshared signal may be an example of a NOMA signal, and may be transmittedusing a DFT-s-OFDM waveform, a CP-OFDM waveform, or some combination ofthese or other waveforms.

Base station 105-b may monitor the channel for candidate signals to testfor uplink data. When base station 105-b receives the shared signal,base station 105-b may determine at least one of the one or morepreamble layers scrambled in the candidate signal (e.g., at 530). Forexample, base station 105-b may determine a set of signature sequencesfor detecting the one or more preamble layers, and may descramble thepreamble layers from the candidate signal based on these signaturesequences. In some cases, base station 105-b may include an indicationof expected preamble values stored in memory. Base station 105-b maycompare the expected preamble values to the one or more preamble layersin order to determine one or more received preamble layers.

At 535, base station 105-b may decode the one or more data layers basedon the determined preamble layers. In some cases, base station 105-b mayperform channel estimation for the candidate signal using the preamblelayers (and any received reference signals corresponding to thecandidate signal), and may decode the data layers based on this channelestimation. In other cases, base station 105-b may jointly decode thepreamble layers and data layers, using the preamble layers as priorinformation for a message-passing procedure. In some examples, basestation 105-b may determine a set of signature sequences correspondingto the data layers, and may descrambled the data layers based on thesesequences.

FIG. 6 shows a block diagram 600 of a wireless device 605 that supportsparallel transmission of preamble sequences with data layers forimproved data detection in accordance with aspects of the presentdisclosure. Wireless device 605 may be an example of aspects of a UE 115as described herein. Wireless device 605 may include receiver 610, UEparallel transmission handling component 615, and transmitter 620.Wireless device 605 may also include a processor. Each of thesecomponents may be in communication with one another (e.g., via one ormore buses).

Receiver 610 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to paralleltransmission of preamble sequences with data layers for improved datadetection). Information may be passed on to other components of thedevice. The receiver 610 may be an example of aspects of the transceiver935 described with reference to FIG. 9. The receiver 610 may utilize asingle antenna or a set of antennas.

UE parallel transmission handling component 615 may be an example ofaspects of the UE parallel transmission handling component 715, 815, or915 described with reference to FIGS. 7 through 9.

UE parallel transmission handling component 615 and/or at least some ofits various sub-components may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions of the UEparallel transmission handling component 615 and/or at least some of itsvarious sub-components may be executed by a general-purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), an field-programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described in the present disclosure. The UE paralleltransmission handling component 615 and/or at least some of its varioussub-components may be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations by one or more physical devices.

In some examples, UE parallel transmission handling component 615 and/orat least some of its various sub-components may be a separate anddistinct component in accordance with various aspects of the presentdisclosure. In other examples, UE parallel transmission handlingcomponent 615 and/or at least some of its various sub-components may becombined with one or more other hardware components, including but notlimited to an I/O component, a transceiver, a network server, anothercomputing device, one or more other components described in the presentdisclosure, or a combination thereof in accordance with various aspectsof the present disclosure.

UE parallel transmission handling component 615 may identify one or moredata layers and one or more preamble layers for transmission, determinea set of signature sequences for scrambling the one or more data layersand the one or more preamble layers, assign each signature sequence ofthe set of signature sequences to a data layer of the one or more datalayers or a preamble layer of the one or more preamble layers based on across-correlation metric of each signature sequence, scramble the one ormore data layers and the one or more preamble layers into a sharedsignal using each assigned signature sequence, and transmit the sharedsignal.

Transmitter 620 may transmit signals generated by other components ofthe device. In some examples, the transmitter 620 may be collocated witha receiver 610 in a transceiver component. For example, the transmitter620 may be an example of aspects of the transceiver 935 described withreference to FIG. 9. The transmitter 620 may utilize a single antenna ora set of antennas.

FIG. 7 shows a block diagram 700 of a wireless device 705 that supportsparallel transmission of preamble sequences with data layers forimproved data detection in accordance with aspects of the presentdisclosure. Wireless device 705 may be an example of aspects of awireless device 605 or a UE 115 as described with reference to FIGS. 1through 6. Wireless device 705 may include receiver 710, UE paralleltransmission handling component 715, and transmitter 720. Wirelessdevice 705 may also include a processor. Each of these components may bein communication with one another (e.g., via one or more buses).

Receiver 710 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to paralleltransmission of preamble sequences with data layers for improved datadetection). Information may be passed on to other components of thedevice. The receiver 710 may be an example of aspects of the transceiver935 described with reference to FIG. 9. The receiver 710 may utilize asingle antenna or a set of antennas.

UE parallel transmission handling component 715 may be an example ofaspects of the UE parallel transmission handling component 615, 815, or915 described with reference to FIGS. 6, 8, and 9. UE paralleltransmission handling component 715 may also include layeridentification component 725, signature sequence determination component730, signature sequence assignment component 735, scrambling component740, and transmission component 745.

Layer identification component 725 may identify one or more data layersand one or more preamble layers for transmission. Signature sequencedetermination component 730 may determine a set of signature sequencesfor scrambling the one or more data layers and the one or more preamblelayers. Signature sequence assignment component 735 may assign eachsignature sequence of the set of signature sequences to a data layer ofthe one or more data layers or a preamble layer of the one or morepreamble layers based on a cross-correlation metric of the eachsignature sequence. Scrambling component 740 may scramble the one ormore data layers and the one or more preamble layers into a sharedsignal using the assigned each signature sequence. Transmissioncomponent 745 may transmit the shared signal.

Transmitter 720 may transmit signals generated by other components ofthe device. In some examples, the transmitter 720 may be collocated witha receiver 710 in a transceiver component. For example, the transmitter720 may be an example of aspects of the transceiver 935 described withreference to FIG. 9. The transmitter 720 may utilize a single antenna ora set of antennas.

FIG. 8 shows a block diagram 800 of a UE parallel transmission handlingcomponent 815 that supports parallel transmission of preamble sequenceswith data layers for improved data detection in accordance with aspectsof the present disclosure. The UE parallel transmission handlingcomponent 815 may be an example of aspects of a UE parallel transmissionhandling component 615, 715, or 915 described with reference to FIGS. 6,7, and 9. The UE parallel transmission handling component 815 mayinclude layer identification component 820, signature sequencedetermination component 825, signature sequence assignment component830, scrambling component 835, transmission component 840, signaturesequence reception component 845, signature sequence selection component850, and signal generation component 855. Each of these components maycommunicate, directly or indirectly, with one another (e.g., via one ormore buses).

Layer identification component 820 may identify one or more data layersand one or more preamble layers for transmission. In some cases, apreamble of the one or more preamble layers includes a default value, apre-determined sequence, a pseudo-random sequence, or a combinationthereof.

Signature sequence determination component 825 may determine a set ofsignature sequences for scrambling the one or more data layers and theone or more preamble layers. In some cases, the set of signaturesequences includes orthogonal signature sequences, non-orthogonalsignature sequences, or a combination thereof.

Signature sequence assignment component 830 may assign each signaturesequence of the set of signature sequences to a data layer of the one ormore data layers or a preamble layer of the one or more preamble layersbased on a cross-correlation metric of the each signature sequence. Insome cases, assigning the each signature sequence of the set ofsignature sequences to the data layer of the one or more data layers orthe preamble layer of the one or more preamble layers further includessignature sequence assignment component 830 assigning a first set ofsignature sequences of the set of signature sequences to the one or moredata layers, the first set of signature sequences corresponding tocross-correlation values that are lower than cross-correlation values ofa second set of signature sequences of the set of signature sequences.Signature sequence assignment component 830 may additionally assign thesecond set of signature sequences to the one or more preamble layers.

Scrambling component 835 may scramble the one or more data layers andthe one or more preamble layers into a shared signal using the assignedeach signature sequence.

Transmission component 840 may transmit the shared signal. In somecases, transmission component 840 may additionally transmit one or moreDMRSs prior to transmitting the shared signal, where the one or moreDMRSs include information for detecting the shared signal. In othercases, the shared signal may be an example of a self-decodable signal.In some cases, transmitting the shared signal includes transmitting theshared signal using a DFT-s-OFDM waveform, a CP-OFDM waveform, or acombination thereof. In some cases, the shared signal is an example of aNOMA signal.

Signature sequence reception component 845 may receive a signaturesequence allocation message from a base station, where the set ofsignature sequences is determined according to the signature sequenceallocation message.

Signature sequence selection component 850 may select the set ofsignature sequences from a signature sequence pool, where the set ofsignature sequences is determined according to the selecting. In somecases, selecting the set of signature sequences from the signaturesequence pool is based on a pseudo-random selection procedure.

In some cases, signal generation component 855 may assign differentmodulation schemes, channel coding schemes, power allocations, or acombination thereof to the one or more data layers, the one or morepreamble layers, or a combination thereof. For example, signalgeneration component 855 may dynamically configure the modulationschemes, channel coding schemes, power allocations, or the combinationthereof each layer of the one or more data layers, the one or morepreamble layers, or the combination thereof, where assigning thedifferent modulation schemes, the channel coding schemes, the powerallocations, or the combination thereof is based on the dynamicconfiguration. In other cases, signal generation component 855 mayassign a same modulation scheme, channel coding scheme, powerallocation, or a combination thereof to the one or more data layers, theone or more preamble layers, or a combination thereof.

FIG. 9 shows a diagram of a system 900 including a device 905 thatsupports parallel transmission of preamble sequences with data layersfor improved data detection in accordance with aspects of the presentdisclosure. Device 905 may be an example of or include the components ofwireless device 605, wireless device 705, or a UE 115 as describedabove, e.g., with reference to FIGS. 1 through 7. Device 905 may includecomponents for bi-directional voice and data communications includingcomponents for transmitting and receiving communications, including UEparallel transmission handling component 915, processor 920, memory 925,software 930, transceiver 935, antenna 940, and I/O controller 945.These components may be in electronic communication via one or morebuses (e.g., bus 910). Device 905 may communicate wirelessly with one ormore base stations 105.

Processor 920 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a central processing unit (CPU), amicrocontroller, an ASIC, an FPGA, a programmable logic device, adiscrete gate or transistor logic component, a discrete hardwarecomponent, or any combination thereof). In some cases, processor 920 maybe configured to operate a memory array using a memory controller. Inother cases, a memory controller may be integrated into processor 920.Processor 920 may be configured to execute computer-readableinstructions stored in a memory to perform various functions (e.g.,functions or tasks supporting parallel transmission of preamblesequences with data layers for improved data detection).

Memory 925 may include random access memory (RAM) and read only memory(ROM). The memory 925 may store computer-readable, computer-executablesoftware 930 including instructions that, when executed, cause theprocessor to perform various functions described herein. In some cases,the memory 925 may contain, among other things, a basic input/outputsystem (BIOS) which may control basic hardware or software operationsuch as the interaction with peripheral components or devices.

Software 930 may include code to implement aspects of the presentdisclosure, including code to support parallel transmission of preamblesequences with data layers for improved data detection. Software 930 maybe stored in a non-transitory computer-readable medium such as systemmemory or other memory. In some cases, the software 930 may not bedirectly executable by the processor but may cause a computer (e.g.,when compiled and executed) to perform functions described herein.

Transceiver 935 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 935 may represent a wireless transceiver and may communicatebi-directionally with another wireless transceiver. The transceiver 935may also include a modem to modulate the packets and provide themodulated packets to the antennas for transmission, and to demodulatepackets received from the antennas.

In some cases, the wireless device may include a single antenna 940.However, in some cases the device may have more than one antenna 940,which may be capable of concurrently transmitting or receiving multiplewireless transmissions.

I/O controller 945 may manage input and output signals for device 905.I/O controller 945 may also manage peripherals not integrated intodevice 905. In some cases, I/O controller 945 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 945 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 945 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 945 may be implemented as part of aprocessor. In some cases, a user may interact with device 905 via I/Ocontroller 945 or via hardware components controlled by I/O controller945.

FIG. 10 shows a block diagram 1000 of a wireless device 1005 thatsupports parallel transmission of preamble sequences with data layersfor improved data detection in accordance with aspects of the presentdisclosure. Wireless device 1005 may be an example of aspects of a basestation 105 as described herein. Wireless device 1005 may includereceiver 1010, base station parallel transmission handling component1015, and transmitter 1020. Wireless device 1005 may also include aprocessor. Each of these components may be in communication with oneanother (e.g., via one or more buses).

Receiver 1010 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to paralleltransmission of preamble sequences with data layers for improved datadetection). Information may be passed on to other components of thedevice. The receiver 1010 may be an example of aspects of thetransceiver 1335 described with reference to FIG. 13. The receiver 1010may utilize a single antenna or a set of antennas.

Base station parallel transmission handling component 1015 may be anexample of aspects of the base station parallel transmission handlingcomponent 1115, 1215, or 1315 described with reference to FIGS. 11through 13.

Base station parallel transmission handling component 1015 and/or atleast some of its various sub-components may be implemented in hardware,software executed by a processor, firmware, or any combination thereof.If implemented in software executed by a processor, the functions of thebase station parallel transmission handling component 1015 and/or atleast some of its various sub-components may be executed by ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed in the present disclosure. The base station paralleltransmission handling component 1015 and/or at least some of its varioussub-components may be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations by one or more physical devices. In someexamples, base station parallel transmission handling component 1015and/or at least some of its various sub-components may be a separate anddistinct component in accordance with various aspects of the presentdisclosure. In other examples, base station parallel transmissionhandling component 1015 and/or at least some of its varioussub-components may be combined with one or more other hardwarecomponents, including but not limited to an I/O component, atransceiver, a network server, another computing device, one or moreother components described in the present disclosure, or a combinationthereof in accordance with various aspects of the present disclosure.

Base station parallel transmission handling component 1015 may receive acandidate signal from a UE, determine one or more preamble layersscrambled in the candidate signal, and decode one or more data layersscrambled in the candidate signal based on the one or more preamblelayers.

Transmitter 1020 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1020 may be collocatedwith a receiver 1010 in a transceiver component. For example, thetransmitter 1020 may be an example of aspects of the transceiver 1335described with reference to FIG. 13. The transmitter 1020 may utilize asingle antenna or a set of antennas.

FIG. 11 shows a block diagram 1100 of a wireless device 1105 thatsupports parallel transmission of preamble sequences with data layersfor improved data detection in accordance with aspects of the presentdisclosure. Wireless device 1105 may be an example of aspects of awireless device 1005 or a base station 105 as described with referenceto FIGS. 1 through 5 and 10. Wireless device 1105 may include receiver1110, base station parallel transmission handling component 1115, andtransmitter 1120. Wireless device 1105 may also include a processor.Each of these components may be in communication with one another (e.g.,via one or more buses).

Receiver 1110 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to paralleltransmission of preamble sequences with data layers for improved datadetection). Information may be passed on to other components of thedevice. The receiver 1110 may be an example of aspects of thetransceiver 1335 described with reference to FIG. 13. The receiver 1110may utilize a single antenna or a set of antennas.

Base station parallel transmission handling component 1115 may be anexample of aspects of the base station parallel transmission handlingcomponent 1015, 1215, or 1315 described with reference to FIGS. 10, 12,and 13. Base station parallel transmission handling component 1115 mayalso include reception component 1125, preamble layer component 1130,and data layer component 1135.

Reception component 1125 may receive a candidate signal from a UE. Insome cases, the candidate signal is an example of a shared signal.Preamble layer component 1130 may determine one or more preamble layersscrambled in the candidate signal. Data layer component 1135 may decodeone or more data layers scrambled in the candidate signal based on theone or more preamble layers.

Transmitter 1120 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1120 may be collocatedwith a receiver 1110 in a transceiver component. For example, thetransmitter 1120 may be an example of aspects of the transceiver 1335described with reference to FIG. 13. The transmitter 1120 may utilize asingle antenna or a set of antennas.

FIG. 12 shows a block diagram 1200 of a base station paralleltransmission handling component 1215 that supports parallel transmissionof preamble sequences with data layers for improved data detection inaccordance with aspects of the present disclosure. The base stationparallel transmission handling component 1215 may be an example ofaspects of a base station parallel transmission handling component 1015,1115, or 1315 described with reference to FIGS. 10, 11, and 13. The basestation parallel transmission handling component 1215 may includereception component 1220, preamble layer component 1225, data layercomponent 1230, message-passing component 1235, channel estimationcomponent 1240, signature sequence transmission component 1245, andreference signal component 1250. Each of these components maycommunicate, directly or indirectly, with one another (e.g., via one ormore buses).

Reception component 1220 may receive a candidate signal from a UE. Insome cases, the candidate signal is a self-decodable signal. In somecases, the candidate signal is an example of a NOMA signal. In somecases, the candidate signal is an example of a shared signal.

Preamble layer component 1225 may determine one or more preamble layersscrambled in the candidate signal. In some cases, preamble layercomponent 1225 may determine a set of signature sequences for detectingthe one or more preamble layers, and may descramble the one or morepreamble layers from the candidate signal based on the set of signaturesequences, where determining the one or more preamble layers scrambledin the candidate signal is based on the descrambling.

Data layer component 1230 may decode one or more data layers scrambledin the candidate signal based on the one or more preamble layers. Insome cases, data layer component 1230 may determine a set of signaturesequences for detecting the one or more data layers, and may descramblethe one or more data layers from the candidate signal based on the setof signature sequences, where decoding the one or more data layersscrambled in the candidate signal is based on the descrambling.

Message-passing component 1235 may jointly decoding the one or morepreamble layers with the one or more data layers. In some cases,decoding the one or more data layers may include message-passingcomponent 1235 performing a message-passing procedure, where the one ormore preamble layers are used as prior information for themessage-passing procedure.

Channel estimation component 1240 may perform channel estimation for thecandidate signal based on the one or more preamble layers, where the oneor more data layers are decoded based on the channel estimation. In somecases, performing the channel estimation for the candidate signalincludes comparing the one or more preamble layers to one or moreexpected preamble values. In some cases, a preamble value of the one ormore expected preamble values includes a default value, a pre-determinedsequence, a pseudo-random sequence, or a combination thereof.

Signature sequence transmission component 1245 may transmit a signaturesequence allocation message to the UE, where the candidate signalreceived from the UE is based on the signature sequence allocationmessage. In some cases, signature sequence transmission component 1245may determine a set of signature sequences, where the signature sequenceallocation message indicates the set of signature sequences and wheredetermining the one or more preamble layers scrambled in the candidatesignal is based on the set of signature sequences.

Reference signal component 1250 may receive one or more DMRSs for thecandidate signal, and may perform channel estimation for the candidatesignal based on the one or more DMRSs, where the one or more data layersare decoded based on the channel estimation.

FIG. 13 shows a diagram of a system 1300 including a device 1305 thatsupports parallel transmission of preamble sequences with data layersfor improved data detection in accordance with aspects of the presentdisclosure. Device 1305 may be an example of or include the componentsof wireless device 1005, wireless device 1105, or a base station 105 asdescribed above, e.g., with reference to FIGS. 1 through 5, 10, and 11.Device 1305 may include components for bi-directional voice and datacommunications including components for transmitting and receivingcommunications, including base station parallel transmission handlingcomponent 1315, processor 1320, memory 1325, software 1330, transceiver1335, antenna 1340, network communications manager 1345, andinter-station communications manager 1350. These components may be inelectronic communication via one or more buses (e.g., bus 1310). Device1305 may communicate wirelessly with one or more UEs 115.

Processor 1320 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, anFPGA, a programmable logic device, a discrete gate or transistor logiccomponent, a discrete hardware component, or any combination thereof).In some cases, processor 1320 may be configured to operate a memoryarray using a memory controller. In other cases, a memory controller maybe integrated into processor 1320. Processor 1320 may be configured toexecute computer-readable instructions stored in a memory to performvarious functions (e.g., functions or tasks supporting paralleltransmission of preamble sequences with data layers for improved datadetection).

Memory 1325 may include RAM and ROM. The memory 1325 may storecomputer-readable, computer-executable software 1330 includinginstructions that, when executed, cause the processor to perform variousfunctions described herein. In some cases, the memory 1325 may contain,among other things, a BIOS which may control basic hardware or softwareoperation such as the interaction with peripheral components or devices.

Software 1330 may include code to implement aspects of the presentdisclosure, including code to support parallel transmission of preamblesequences with data layers for improved data detection. Software 1330may be stored in a non-transitory computer-readable medium such assystem memory or other memory. In some cases, the software 1330 may notbe directly executable by the processor but may cause a computer (e.g.,when compiled and executed) to perform functions described herein.

Transceiver 1335 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 1335 may represent a wireless transceiver and maycommunicate bi-directionally with another wireless transceiver. Thetransceiver 1335 may also include a modem to modulate the packets andprovide the modulated packets to the antennas for transmission, and todemodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 1340.However, in some cases the device may have more than one antenna 1340,which may be capable of concurrently transmitting or receiving multiplewireless transmissions.

Network communications manager 1345 may manage communications with thecore network (e.g., via one or more wired backhaul links). For example,the network communications manager 1345 may manage the transfer of datacommunications for client devices, such as one or more UEs 115.

Inter-station communications manager 1350 may manage communications withother base station 105, and may include a controller or scheduler forcontrolling communications with UEs 115 in cooperation with other basestations 105. For example, the inter-station communications manager 1350may coordinate scheduling for transmissions to UEs 115 for variousinterference mitigation techniques such as beamforming or jointtransmission. In some examples, inter-station communications manager1350 may provide an X2 interface within a Long Term Evolution(LTE)/LTE-A wireless communication network technology to providecommunication between base stations 105.

FIG. 14 shows a flowchart illustrating a method 1400 for paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure. Theoperations of method 1400 may be implemented by a UE 115 or itscomponents as described herein. For example, the operations of method1400 may be performed by a UE parallel transmission handling componentas described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1405 the UE 115 may identify one or more data layers and one or morepreamble layers for transmission. The operations of 1405 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of 1405 may be performed by a layeridentification component as described with reference to FIGS. 6 through9.

At 1410 the UE 115 may determine a set of signature sequences forscrambling the one or more data layers and the one or more preamblelayers. The operations of 1410 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1410may be performed by a signature sequence determination component asdescribed with reference to FIGS. 6 through 9.

At 1415 the UE 115 may assign each signature sequence of the set ofsignature sequences to a data layer of the one or more data layers or apreamble layer of the one or more preamble layers based at least in parton a cross-correlation metric of the each signature sequence. Theoperations of 1415 may be performed according to the methods describedherein. In certain examples, aspects of the operations of 1415 may beperformed by a signature sequence assignment component as described withreference to FIGS. 6 through 9.

At 1420 the UE 115 may scramble the one or more data layers and the oneor more preamble layers into a shared signal using the assigned eachsignature sequence. The operations of 1420 may be performed according tothe methods described herein. In certain examples, aspects of theoperations of 1420 may be performed by a scrambling component asdescribed with reference to FIGS. 6 through 9.

At 1425 the UE 115 may transmit the shared signal. The operations of1425 may be performed according to the methods described herein. Incertain examples, aspects of the operations of 1425 may be performed bya transmission component as described with reference to FIGS. 6 through9.

FIG. 15 shows a flowchart illustrating a method 1500 for paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure. Theoperations of method 1500 may be implemented by a UE 115 or itscomponents as described herein. For example, the operations of method1500 may be performed by a UE parallel transmission handling componentas described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1505 the UE 115 may identify one or more data layers and one or morepreamble layers for transmission. The operations of 1505 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of 1505 may be performed by a layeridentification component as described with reference to FIGS. 6 through9.

At 1510 the UE 115 may determine a set of signature sequences forscrambling the one or more data layers and the one or more preamblelayers. The operations of 1510 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1510may be performed by a signature sequence determination component asdescribed with reference to FIGS. 6 through 9.

At 1515 and 1520 the UE 115 may assign each signature sequence of theset of signature sequences to a data layer of the one or more datalayers or a preamble layer of the one or more preamble layers based atleast in part on a cross-correlation metric of the each signaturesequence. For example, at 1515, the UE 115 may assign a first set ofsignature sequences of the set of signature sequences to the one or moredata layers, the first set of signature sequences corresponding tocross-correlation values that are lower than cross-correlation values ofa second set of signature sequences of the set of signature sequences.The operations of 1515 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1515may be performed by a signature sequence assignment component asdescribed with reference to FIGS. 6 through 9. At 1520 the UE 115 mayassign the second set of signature sequences to the one or more preamblelayers. The operations of 1520 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1520may be performed by a signature sequence assignment component asdescribed with reference to FIGS. 6 through 9.

At 1525 the UE 115 may scramble the one or more data layers and the oneor more preamble layers into a shared signal using the assigned eachsignature sequence. The operations of 1525 may be performed according tothe methods described herein. In certain examples, aspects of theoperations of 1525 may be performed by a scrambling component asdescribed with reference to FIGS. 6 through 9.

At 1530 the UE 115 may transmit the shared signal. The operations of1530 may be performed according to the methods described herein. Incertain examples, aspects of the operations of 1530 may be performed bya transmission component as described with reference to FIGS. 6 through9.

FIG. 16 shows a flowchart illustrating a method 1600 for paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure. Theoperations of method 1600 may be implemented by a base station 105 orits components as described herein. For example, the operations ofmethod 1600 may be performed by a base station parallel transmissionhandling component as described with reference to FIGS. 10 through 13.In some examples, a base station 105 may execute a set of codes tocontrol the functional elements of the device to perform the functionsdescribed below. Additionally or alternatively, the base station 105 mayperform aspects of the functions described below using special-purposehardware.

At 1605 the base station 105 may receive a candidate signal from a UE115. The operations of 1605 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1605may be performed by a reception component as described with reference toFIGS. 10 through 13.

At 1610 the base station 105 may determine one or more preamble layersscrambled in the candidate signal. The operations of 1610 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of 1610 may be performed by apreamble layer component as described with reference to FIGS. 10 through13.

At 1615 the base station 105 may decode one or more data layersscrambled in the candidate signal based at least in part on the one ormore preamble layers. The operations of 1615 may be performed accordingto the methods described herein. In certain examples, aspects of theoperations of 1615 may be performed by a data layer component asdescribed with reference to FIGS. 10 through 13.

FIG. 17 shows a flowchart illustrating a method 1700 for paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure. Theoperations of method 1700 may be implemented by a base station 105 orits components as described herein. For example, the operations ofmethod 1700 may be performed by a base station parallel transmissionhandling component as described with reference to FIGS. 10 through 13.In some examples, a base station 105 may execute a set of codes tocontrol the functional elements of the device to perform the functionsdescribed below. Additionally or alternatively, the base station 105 mayperform aspects of the functions described below using special-purposehardware.

At 1705 the base station 105 may receive a candidate signal from a UE115. The operations of 1705 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1705may be performed by a reception component as described with reference toFIGS. 10 through 13.

At 1710 the base station 105 may jointly decode one or more preamblelayers with one or more data layers scrambled in the candidate signal.The operations of 1710 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1710may be performed by a message-passing component as described withreference to FIGS. 10 through 13.

At 1715 the base station 105 may perform a message-passing procedure,where the one or more preamble layers are used as prior information forthe message-passing procedure. The operations of 1715 may be performedaccording to the methods described herein. In certain examples, aspectsof the operations of 1715 may be performed by a message-passingcomponent as described with reference to FIGS. 10 through 13.

At 1720 the base station 105 may decode one or more data layersscrambled in the candidate signal based at least in part on themessage-passing procedure. The operations of 1720 may be performedaccording to the methods described herein. In certain examples, aspectsof the operations of 1720 may be performed by a data layer component asdescribed with reference to FIGS. 10 through 13.

FIG. 18 shows a flowchart illustrating a method 1800 for paralleltransmission of preamble sequences with data layers for improved datadetection in accordance with aspects of the present disclosure. Theoperations of method 1800 may be implemented by a base station 105 orits components as described herein. For example, the operations ofmethod 1800 may be performed by a base station parallel transmissionhandling component as described with reference to FIGS. 10 through 13.In some examples, a base station 105 may execute a set of codes tocontrol the functional elements of the device to perform the functionsdescribed below. Additionally or alternatively, the base station 105 mayperform aspects of the functions described below using special-purposehardware.

At 1805 the base station 105 may receive a candidate signal from a UE115. The operations of 1805 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1805may be performed by a reception component as described with reference toFIGS. 10 through 13.

At 1810 the base station 105 may determine one or more preamble layersscrambled in the candidate signal. The operations of 1810 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of 1810 may be performed by apreamble layer component as described with reference to FIGS. 10 through13.

At 1815 the base station 105 may perform channel estimation for thecandidate signal based at least in part on the one or more preamblelayers. The operations of 1815 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations of 1815may be performed by a channel estimation component as described withreference to FIGS. 10 through 13.

At 1820 the base station 105 may decode one or more data layersscrambled in the candidate signal based at least in part on the channelestimation. The operations of 1820 may be performed according to themethods described herein. In certain examples, aspects of the operationsof 1820 may be performed by a data layer component as described withreference to FIGS. 10 through 13.

It should be noted that the methods described above describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Further, aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.A CDMA system may implement a radio technology such as CDMA2000, UTRA,etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000Releases may be commonly referred to as CDMA2000 1×, 1×, etc. IS-856(TIA-856) is commonly referred to as CDMA2000 1×EV-DO, High Rate PacketData (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variantsof CDMA. A TDMA system may implement a radio technology such as GlobalSystem for Mobile Communications (GSM).

An OFDMA system may implement a radio technology such as Ultra MobileBroadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical andElectronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are releasesof UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR,and GSM are described in documents from the organization named “3rdGeneration Partnership Project” (3GPP). CDMA2000 and UMB are describedin documents from an organization named “3rd Generation PartnershipProject 2” (3GPP2). The techniques described herein may be used for thesystems and radio technologies mentioned above as well as other systemsand radio technologies. While aspects of an LTE, LTE-A, LTE-A Pro, or NRsystem may be described for purposes of example, and LTE, LTE-A, LTE-APro, or NR terminology may be used in much of the description, thetechniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro,or NR applications.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEs115 with service subscriptions with the network provider. A small cellmay be associated with a lower-powered base station 105, as comparedwith a macro cell, and a small cell may operate in the same or different(e.g., licensed, unlicensed) frequency bands as macro cells. Small cellsmay include pico cells, femto cells, and micro cells according tovarious examples. A pico cell, for example, may cover a small geographicarea and may allow unrestricted access by UEs 115 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessby UEs 115 having an association with the femto cell (e.g., UEs 115 in aclosed subscriber group (CSG), UEs 115 for users in the home, and thelike). An eNB for a macro cell may be referred to as a macro eNB. An eNBfor a small cell may be referred to as a small cell eNB, a pico eNB, afemto eNB, or a home eNB. An eNB may support one or multiple (e.g., two,three, four, and the like) cells, and may also support communicationsusing one or multiple component carriers.

The wireless communications system 100 or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations 105 may have similar frame timing, andtransmissions from different base stations 105 may be approximatelyaligned in time. For asynchronous operation, the base stations 105 mayhave different frame timing, and transmissions from different basestations 105 may not be aligned in time. The techniques described hereinmay be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other programmable logic device (PLD), discretegate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations.

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media maycomprise RAM, ROM, electrically erasable programmable read only memory(EEPROM), flash memory, compact disk (CD) ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother non-transitory medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include CD, laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

As used herein, including in the claims, “or” as used in a list of items(e.g., a list of items prefaced by a phrase such as “at least one of” or“one or more of”) indicates an inclusive list such that, for example, alist of at least one of A, B, or C means A or B or C or AB or AC or BCor ABC (i.e., A and B and C). Also, as used herein, the phrase “basedon” shall not be construed as a reference to a closed set of conditions.For example, an exemplary step that is described as “based on conditionA” may be based on both a condition A and a condition B withoutdeparting from the scope of the present disclosure. In other words, asused herein, the phrase “based on” shall be construed in the same manneras the phrase “based at least in part on.”

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label, or othersubsequent reference label.

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the concepts of thedescribed examples.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notlimited to the examples and designs described herein, but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communications, comprising: identifying one or more data layers and one or more preamble layers for transmission; determining a set of signature sequences for scrambling the one or more data layers and the one or more preamble layers; assigning each signature sequence of the set of signatur sequences to a data layer of the one or more data layers or a preamble layer of the one or more preamble layers based at least in part on a cross-correlation metric of the each signature sequence; scrambling the one or more data layers and the one or more preamble layers into a shared signal using the assigned each signature sequence; and transmitting the shared signal.
 2. The method of claim 1, wherein assigning the each signature sequence of the set of signature sequences to the data layer of the one or more data layers or the preamble layer of the one or more preamble layers further comprises: assigning a first set of signature sequences of the set of signature sequences to the one or more data layers, the first set of signature sequences corresponding to cross-correlation values that are lower than cross-correlation values of a second set of signature sequences of the set of signature sequences; and assigning the second set of signature sequences to the one or more preamble layers.
 3. The method of claim 1, further comprising: receiving a signature sequence allocation message from a base station, wherein the set of signature sequences is determined according to the signature sequence allocation message.
 4. The method of claim 1, further comprising: selecting the set of signature sequences from a signature sequence pool, wherein the set of signature sequences is determined according to the selecting.
 5. The method of claim 4, wherein selecting the set of signature sequences from the signature sequence pool is based at least in part on a pseudo-random selection procedure.
 6. The method of claim 1, further comprising: assigning different modulation schemes, channel coding schemes, power allocations, or a combination thereof to the one or more data layers, the one or more preamble layers, or a combination thereof.
 7. The method of claim 6, further comprising: dynamically configuring the modulation schemes, channel coding schemes, power allocations, or the combination thereof each layer of the one or more data layers, the one or more preamble layers, or the combination thereof, wherein assigning the different modulation schemes, the channel coding schemes, the power allocations, or the combination thereof is based at least in part on the dynamic configuration.
 8. The method of claim 1, further comprising: assigning a same modulation scheme, channel coding scheme, power allocation, or a combination thereof to the one or more data layers, the one or more preamble layers, or a combination thereof.
 9. The method of claim 1, wherein transmitting the shared signal comprises: transmitting the shared signal using a Discrete Fourier Transform-spread-orthogonal frequency division multiplexing (DFT-s-OFDM) waveform, a cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM) waveform, or a combination thereof.
 10. The method of claim 1, further comprising: transmitting one or more demodulation reference signals (DMRSs) prior to transmitting the shared signal, wherein the one or more DMRSs comprise information for detecting the shared signal.
 11. The method of claim 1, wherein the shared signal comprises a self-decodable signal.
 12. The method of claim 1, wherein a preamble of the one or more preamble layers comprises a default value, a pre-determined sequence, a pseudo-random sequence, or a combination thereof.
 13. The method of claim 1, wherein the set of signature sequences comprises orthogonal signature sequences, non-orthogonal signature sequences, or a combination thereof.
 14. The method of claim 1, wherein the shared signal comprises a non-orthogonal multiple access (NOMA) signal.
 15. A method for wireless communications, comprising: receiving a candidate signal from a user equipment (UE); determining one or more preamble layers scrambled in the candidate signal; and decoding one or more data layers scrambled in the candidate signal based at least in part on the one or more preamble layers.
 16. The method of claim 15, further comprising: jointly decoding the one or more preamble layers with the one or more data layers, wherein decoding the one or more data layers comprises: performing a message-passing procedure, wherein the one or more preamble layers are used as prior information for the message-passing procedure.
 17. The method of claim 15, further comprising: performing channel estimation for the candidate signal based at least in part on the one or more preamble layers, wherein the one or more data layers are decoded based at least in part on the channel estimation.
 18. The method of claim 17, wherein performing the channel estimation for the candidate signal comprises: comparing the one or more preamble layers to one or more expected preamble values.
 19. The method of claim 18, wherein a preamble value of the one or more expected preamble values comprises a default value, a pre-determined sequence, a pseudo-random sequence, or a combination thereof.
 20. The method of claim 15, further comprising: transmitting a signatur sequence allocation message to the UE, wherein the candidate signal received from the UE is based at least in part on the signature sequence allocation message.
 21. The method of claim 20, further comprising: determining a set of signature sequences, wherein the signature sequence allocation message indicates the set of signature sequences and wherein determining the one or more preamble layers scrambled in the candidate signal is based at least in part on the set of signature sequences.
 22. The method of claim 15, further comprising: determining a set of signature sequences for detecting the one or more data layers; and descrambling the one or more data layers from the candidate signal based at least in part on the set of signature sequences, wherein decoding the one or more data layers scrambled in the candidate signal is based at least in part on the descrambling.
 23. The method of claim 15, further comprising: receiving one or more demodulation reference signals (DMRSs) for the candidate signal; and performing channel estimation for the candidate signal based at least in part on the one or more DMRSs, wherein the one or more data layers are decoded based at least in part on the channel estimation.
 24. The method of claim 15, further comprising: determining a set of signature sequences for detecting the one or more preamble layers; and descrambling the one or more preamble layers from the candidate signal based at least in part on the set of signature sequences, wherein determining the one or more preamble layers scrambled in the candidate signal is based at least in part on the descrambling.
 25. The method of claim 15, wherein the candidate signal comprises a self-decodable signal.
 26. The method of claim 15, wherein the candidate signal comprises a non-orthogonal multiple access (NOMA) signal.
 27. The method of claim 15, wherein the candidate signal comprises a shared signal.
 28. An apparatus for wireless communications, comprising: a processor; memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: identify one or more data layers and one or more preamble layers for transmission; determine a set of signature sequences for scrambling the one or more data layers and the one or more preamble layers; assign each signature sequence of the set of signature sequences to a data layer of the one or more data layers or a preamble layer of the one or more preamble layers based at least in part on a cross-correlation metric of the each signature sequence; scramble the one or more data layers and the one or more preamble layers into a shared signal using the assigned each signature sequence; and transmit the shared signal.
 29. The apparatus of claim 28, wherein the instructions to assign the each signature sequence of the set of signature sequences to the data layer of the one or more data layers or the preamble layer of the one or more preamble layers further are executable by the processor to cause the apparatus to: assign a first set of signature sequences of the set of signature sequences to the one or more data layers, the first set of signature sequences corresponding to cross-correlation values that are lower than cross-correlation values of a second set of signature sequences of the set of signature sequences; and assign the second set of signature sequences to the one or more preamble layers.
 30. An apparatus for wireless communications, comprising: a processor; memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: receive a candidate signal from a user equipment (UE); determine one or more preamble layers scrambled in the candidate signal; and decode one or more data layers scrambled in the candidate signal based at least in part on the one or more preamble layers. 